Antiplugging mechanism

ABSTRACT

A magnetic field is established within the gear housing of a part of the transmission system of a vehicle. A gear that rotates in the housing when the vehicle is driven, moves through the magnetic field. The gear teeth vary the magnetic flux and these variations are transmitted by a magnetic pickup to a coil. As a particular feature, the pickup is utilized to hold the magnet and coil assembled to the gear housing. The variations in the magnetic field induce a current in the coil. This current is amplified and is used to energize a solenoid having an armature which locks a directional shift level against directional shifting until the solenoid is deenergized. The lever may at all times be shifted to neutral, however.

United States Patent [72] inventor Robert Nemiroff Philadelphia, Pa. [2| Appl. No. 873,536 [22] Filed Nov. 3,1969 [45] Patented Aug. 31, 1971 [73] Assignee Eaton Yale & Towne Cleveland, Ohio [54] ANTIPLUGGING MECHANISM 12 Claims, 3 Drawing Figs.

[52] US. Cl 74/476 [51] int. Cl Fl6h 57/06 [50] Field of Search 74/476, 477, 475, 473, 526

[56] References Cited UNITED STATES PATENTS 1,491,283 4/1924 Alspaugh 74/477 2 19 j 154 r 20 16 \q q :45

jz J0 Primary Examiner-Milton Kaufman Atmrney-Teagno 84 Toddy ABSTRACT: A magnetic field is established within the gear housing of a part of the transmission system of a vehicle. A gear that rotates in the housing when the vehicle is driven, moves through the magnetic field. The gear teeth vary the magnetic flux and these variations are transmitted by a magnetic pickup to a coil. As a particular feature, the pickup is utilized to hold the magnet and coil assembled to the gear housing. The variations in the magnetic field induce a current in the coil. This current is amplified and is used to energize a solenoid having an armature which locks a directional shift level against directional shifting until the solenoid is deenergized. The lever may at all times be shifted to neutral, however.

ANTIPLUGGING MECHANISM BACKGROUND OF INVENTION This invention relates to means for preventing the reversal of the direction of movement of a vehicle, until the vehicle is brought substantially to a stop. Mechanisms of the particular class are called antiplugging devices, and are well known. It is obvious that particularly in trucks having hydraulic transmissions, the direction of drive may be readily reversed by simply moving the directional control lever. This makes it unnecessary for the operator to use the effort required to apply the brake to bring the truck to a halt, prior to changing direction. Considerable damage to the truck may be caused by reversal during movement, and for that reason a very effective simple antiplugging construction is highly desirable.

PRIOR ART Naturally, there is much prior art in the particular field, and there are many patents illustrating antiplugging constructions. So far as I am aware, thereisno really pertinent prior art that relates to the two most importantfeaturesof my invention, involving the use of electric current induced through the variation of the flux of a magnetic field by a gear of the truck, and a control construction wherebythe directional shift lever may be moved into a neutral position at all times, even though prevented from reversingthe direction ofmovement of the truck.

' OUTLINE OF THE INVENTION As already indicated, one feature of my invention is the utilization of current induced through the movement of a gear in a magnetic field. Thus, in my invention, I establish a magnetic field, preferably in the differential housing, so that the main differential gear rotating in the housing, will continuously vary the magnetic flux as the teeth of the gear pass through the magnetic field. The variations in the magnetic field ,are transmitted through means of a simple device through a coil so as to generate an electric current that will flow from the coil into an amplifying circuit, where it is amplified for use in controlling the shift device of my invention.

As particular feature of the invention, the device for transmitting variations of the magnetic field into the coil is a magnetic pickup that is actually utilized also to hold the magnet and the coil as well as the pickup itself in a suitable operative position. This simplifies the installation of my invention in a vehicle. I

A further feature of the invention is a limit device for locking the directional shift mechanism against movement from one directional position into an opposed directional position, while yet permitting the movement of the mechanism into neutral. Preferably, I utilize a simple shift lever that is always movable into neutral position, but cannot be moved from one directional position into neutral and then into an opposed directional position, until the vehicle hasbeen brought to a stop.

As a particular feature of this part of the invention, I utilize a simple plate equipped with a slot. By locking the plate in either of two positions, the slot is so placed that in each position, the directional shift lever may be moved from a forward or reverse position into neutral, but not from forward to reverse or vice versa.

DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic view of my invention showing the means for generating the magnetic field, the amplifying circuit, the shift lever, and the means for controlling the movement of the shill lever.

FIG. 2 is a plan view of the mechanism shown in FIG. I for controlling the movement of the shift lever.

FIG. 3 is a view similar to FIG. 2, but showing the slide that controls the shift lever in a different control position.

ing plate 33 locked in its position of FIG. 2,

DESCRIPTION OF A PREFERRED FORM OF THE INVENTION Referring now more particularly to the drawings, reference numeral 10 indicates generally part of a banjo housing for a differential of standard construction. The differential in the housing 10 is not shown, being of standard construction and driven by a main difierential ring gear 11. An opening is formed in the wall of the banjo housing 10, and driven into this opening so as to be retained therein, is a brass sleeve 12. It will be understood that the banjo housing 10 and gear 11 will be of steel, as is common in the art. The brass sleeve 12 will be nonmagnetic and acts as a magnetic insulator.

A magnetic pickup in the form of a steel bolt 13 having a large head 14, traverses a bore 15 of the insulating sleeve 12, and traverses also a coil 16, the lower flange 17 of which lies against the upper end of sleeve 12. A suitable magnet 18 lies through an insulating washer 19 against the upper flange 20 of the coil 16, while bolt 13 passes vertically through an opening 21 in the magnet 18 as clearly shown. In the embodiment illustrated, magnet 18 is U-shaped and its two legs 18a and 18b are applied against the outer surface of the banjo housing 10, being there held secured through the medium of a nut 25 that is applied to the threaded end of the bolt 13.

It is obvious that when the nut 25 is tightened, it will clamp the magnet 18 securely to banjo housing 10, with the bolt head 14 lying against the lower end surface of the insulating sleeve 12. The entire coil and magnet assembly will then be held securely to the sleeve 12, with the sleeve 12 itself securely held relatively to the banjo housing 10.

It is clear that as the gear 11 rotates incidental to the movement of the vehicle of which it is a part, teeth 11 will vary the magnetic flux of the magnetic field established by magnet 18. Bolt 13 will transmit these variations through coil 16, obviously generating electric current, which current flows to a cas- I R5, together with a capacitor C2. The amplified current is fed to a discriminator network consisting of capacitors C3 and C4,

diodes D2 and D3, and resistors R6 and R7. When the speed I of the differential gear is above a preset value, the discriminator network operates transistor Q1 to on. Transistor Q1 then turns on transistor 02 through resistor R8. Transistor 02 then energizes the solenoid 30. Diode D1, capacitor C1 and resistor R9 supply a regulated voltage to'the amplifier and the discriminator network to ensure stable operation. Diode D4 is preferably used with several other parts to suppress signals from other parts of the vehicle. The parts are not shown because they do not alter the operation of the circuit.

It appears rather clearly, therefore, that when the gear 1 1 is moving at a particular speed, it will generate a current that will be amplified to energize a solenoid 30 best seen in FIG. 1. The armature 35 of the solenoid 30, when the solenoid is energized, will enter either an opening 31, or an opening 32 of a limit device in the form of a sliding plate 33. Plate 33 is suitably guided by lugs 34 carried by a baseplate 36 on which plate 33 slides. In FIG. 2, the sliding plate 33 is shown ina position with the armature 35 of solenoid 30 within the opening 32, as to lock plate 33 in its position illustrated in FIG. I.

The sliding plate 33 has a shift opening 40 within which is positioned a shift lever 41, which as shown in FIG. I, is

mounted for movement relatively to a control box B. When the shift lever 41 is in the full line position illustrated in FIG. 2, at the left end of the slot 40, it may be considered that the means set by the shift lever within box B operate to control the truck transmission to drive the truck forwardly. With the slidit will be appreciated that the shift lever 41 may readily be moved to the right into its dotted line position illustrated in FIG. 2. In this dotted line position, the shift lever will be in neutral, and the vehicle will not be driven by its engine in either direction through the transmission controlled by the shift lever 41. In other words, with the solenoid 30 actuated, and plate 33 locked thereby, because the vehicle is moving, it is possible to move theshift lever 41 between forward and neutral. However, because the sliding plate 33 is locked against further movement to the right from its position of FIG. 2, it is not possible to bring the shift lever 41 to the right-beyond its neutral position illustrated in FIG. 2.

If the vehicle is brought to a halt, it is obvious that the solenoid 30 will no longer be energized, and that its armature 35 will drop out of the opening 32. It is now possible for the shift lever 41 to move to its position shown in full lines in FIG. 3. Now, the mechanism within the box B has conditioned the transmission for driving the truck rearwardly. Let us say that the operator now drives the truck rearwardly. This naturally reenergizes the solenoid 30 because gear 11 rotates, and the sliding plate 33 is locked by armature 35 entering hole 31 as shown in FIG. 3. Now, the shift lever 41 can still be moved to the left to its dotted line position, which is the same position shown in dotted lines in FIG. 2. This puts the transmission into neutraL Of course, the shift lever can now be moved back to rearward driving position. Movement of the shift lever back to its position to drive forwardly as in FIG. 2 is not possible, however, because the armature 35 holds the plate 33 locked.

' I believe it will now beunderstood that through the very simple mechanism of my invention, it is possible to prevent plugging of a transmission. In other words, to change direction, the vehicle equipped with my invention must be brought to a halt to deenergize the solenoid 30 and to release the plate 33 so that it may be moved by the shift lever 41. The simple mechanism utilized for the generation of a magnetic field may very easily be installed in a vehicle by the mere expedient of forming a hole for the insulating sleeve 12 in any gear housing. The control of the directional shift lever is most simple and allows movement of the shift lever to neutral at all times, while preventing plugging. I believe that the very considerable merits of my invention will be appreciated by those skilled in the art.

I claim:

1. In a vehicle of the class described the combination of a transmission including a toothed gear, a direction shift device for controlling the direction of drive of said transmission, means for establishing a magnetic field through which said gear rotates whereby changes in the magnetic field are made by the teeth of said gear as it rotates, and means for utilizing said changes in the magnetic field for controlling movement of said shift device.

2. The combination of claim 1, the feature that said shift device moves between two opposed extreme positions and a neutral intermediate position, and said means for controlling movement of said shift device comprising a detent for limiting movement of said shift device to the space between said neutral position and one or the other of said opposed positions.

3. The combination of claim 2, the feature that said means for utilizing changes in said magnetic field comprise means for generating electric current from said changes, means for amplifying said current, and an electromagnet actuated by said amplified current for operating said detent.

4. The combination of claim 2, the feature that said detent locks a slidingmember in either of two spaced positions, said sliding member having an opening relatively to which said shift device moves, whereby when said sliding member is locked in either of its two positions, said shift device may move relatively to said opening in each of the two positions of said sliding member.

5. The combination of claim 1, the feature that said mans for utilizing changes in said magnetic field comprise means for generating electric current from said changes,'means for amplifying said current, and means operated by said amplified current controlling movement of said shift device.

6. The combination of claim 5, the feature that said gear rotates in a casing, and said means for utilizing changes in said magnetic field include also a nonmagnetic bushing in the wall of said casing, and a coil traversed by a magnetic pickup whereby changes in the magnetic field caused by rotation of said gear, are transmitted through said pickup to induce current flow in said coil.

7. The combination of claim 5, the feature that said means operated by said amplified current is an electromagnet and an armature, a sliding member locked by said armature in either of two spaced positions, said sliding member having an opening relatively to which said shift device moves, whereby when said sliding member is locked in either of its two positions, said shift device may move relatively to said opening in each of two positions of said sliding member.

8. The combination of claim 7, the feature that said sliding member is moved to said two spaced positions by said shift device when said sliding member is released from the armature of said electromagnet.

9. In the combination of claim 1, the feature that said means for establishing said magnetic field include a nonmagnetic sleeve held in an opening in the wall of a housing in which said gear rotates, a magnetic pickup passing through the bore of said sleeve and having a head applied to the end of the sleeve.

inward of said housing, a coil and a magnet traversed by the pickup positioned outward of said sleeve and housing and fitted on said pickup, and means on said pickup securing said magnet and coil relatively to said pickup and therefore to said housing and said sleeve, with said magnet establishing said magnetic field.

10. In a combination of the class described, a shift device for a vehicle transmission, a limit device movable by said shift device between two extreme positions as said shift device itself moves between extreme positions, a detent for locking said limit device in each of its two extreme positions, and said limit device being formed relatively to said shift device for permitting limited movement of said shift device in each ofthe said locked positions.

11. In the combination of claim 10, the feature that said transmission has a toothed gear, means for establishing a magnetic field through which said gear rotates whereby changes in the magnetic field are made by the teeth of said gear as it rotates, and means for utilizing said changes in the magnetic field for generating electric current to be used for effecting the operation of said detent to lock said limit device.

12. In the combination of claim 10, the feature that said limit device has a slot in which said shift device slides in either of the locked positions of said limit device, and one end of said slot lying in a position to permit movement of said shift device to neutral in either of the locked'positions of said limit device. 

1. In a vehicle of the class described the combination of a transmission including a toothed gear, a direction shift device for controlling the direction of drive of said transmission, means for establishing a magnetic field through which said gear rotates whereby changes in the magnetic field are made by the teeth Of said gear as it rotates, and means for utilizing said changes in the magnetic field for controlling movement of said shift device.
 2. The combination of claim 1, the feature that said shift device moves between two opposed extreme positions and a neutral intermediate position, and said means for controlling movement of said shift device comprising a detent for limiting movement of said shift device to the space between said neutral position and one or the other of said opposed positions.
 3. The combination of claim 2, the feature that said means for utilizing changes in said magnetic field comprise means for generating electric current from said changes, means for amplifying said current, and an electromagnet actuated by said amplified current for operating said detent.
 4. The combination of claim 2, the feature that said detent locks a sliding member in either of two spaced positions, said sliding member having an opening relatively to which said shift device moves, whereby when said sliding member is locked in either of its two positions, said shift device may move relatively to said opening in each of the two positions of said sliding member.
 5. The combination of claim 1, the feature that said mans for utilizing changes in said magnetic field comprise means for generating electric current from said changes, means for amplifying said current, and means operated by said amplified current controlling movement of said shift device.
 6. The combination of claim 5, the feature that said gear rotates in a casing, and said means for utilizing changes in said magnetic field include also a nonmagnetic bushing in the wall of said casing, and a coil traversed by a magnetic pickup whereby changes in the magnetic field caused by rotation of said gear, are transmitted through said pickup to induce current flow in said coil.
 7. The combination of claim 5, the feature that said means operated by said amplified current is an electromagnet and an armature, a sliding member locked by said armature in either of two spaced positions, said sliding member having an opening relatively to which said shift device moves, whereby when said sliding member is locked in either of its two positions, said shift device may move relatively to said opening in each of two positions of said sliding member.
 8. The combination of claim 7, the feature that said sliding member is moved to said two spaced positions by said shift device when said sliding member is released from the armature of said electromagnet.
 9. In the combination of claim 1, the feature that said means for establishing said magnetic field include a nonmagnetic sleeve held in an opening in the wall of a housing in which said gear rotates, a magnetic pickup passing through the bore of said sleeve and having a head applied to the end of the sleeve inward of said housing, a coil and a magnet traversed by the pickup positioned outward of said sleeve and housing and fitted on said pickup, and means on said pickup securing said magnet and coil relatively to said pickup and therefore to said housing and said sleeve, with said magnet establishing said magnetic field.
 10. In a combination of the class described, a shift device for a vehicle transmission, a limit device movable by said shift device between two extreme positions as said shift device itself moves between extreme positions, a detent for locking said limit device in each of its two extreme positions, and said limit device being formed relatively to said shift device for permitting limited movement of said shift device in each of the said locked positions.
 11. In the combination of claim 10, the feature that said transmission has a toothed gear, means for establishing a magnetic field through which said gear rotates whereby changes in the magnetic field are made by the teeth of said gear as it rotates, and means for utilizing said changes in the magnetic field for generating electric current to be used for effecting the operation of said detent to lock said limIt device.
 12. In the combination of claim 10, the feature that said limit device has a slot in which said shift device slides in either of the locked positions of said limit device, and one end of said slot lying in a position to permit movement of said shift device to neutral in either of the locked positions of said limit device. 